1. Field of the Invention
The present invention relates to an apparatus and a method that record information on an information disk or reproduce the information from the information disk. More particularly, the present invention relates to an apparatus and a method that record and reproduce information on/from an information disk using holography.
2. Description of the Related Art
For holographic recording techniques, there is JP 2008-84486 (Patent Literature 1), for example. This publication describes that “A servo layer 5 includes a phase-change layer as will be described later, and the phase-change layer has servo information recorded therein as phase changes ((changes between crystalline and amorphous phases). In other words, the servo layer 5 has servo information recorded therein as changes in reflectivity with respect to a servo optical beam, i.e., changes in reflectivity that can only be determined by irradiation with a servo optical beam, which are caused by phase changes in the phase-change layer. The servo information includes information for performing a servo (particularly, a tracking servo) in an optical recording and reproducing apparatus and address information, and is recorded in the servo layer 5 in the form of servo marks or servo tracks made by phase changes in the phase-change layer.”